Esempio n. 1
0
        public bool Decode(StreamManipulator input)
        {
decode_loop:
            for (;;)
            {
                switch (mode)
                {
                case LNUM:
                    lnum = input.PeekBits(5);
                    if (lnum < 0)
                    {
                        return(false);
                    }
                    lnum += 257;
                    input.DropBits(5);
                    //          System.err.println("LNUM: "+lnum);
                    mode = DNUM;
                    goto case DNUM;                                     // fall through

                case DNUM:
                    dnum = input.PeekBits(5);
                    if (dnum < 0)
                    {
                        return(false);
                    }
                    dnum++;
                    input.DropBits(5);
                    //          System.err.println("DNUM: "+dnum);
                    num         = lnum + dnum;
                    litdistLens = new byte[num];
                    mode        = BLNUM;
                    goto case BLNUM;                                     // fall through

                case BLNUM:
                    blnum = input.PeekBits(4);
                    if (blnum < 0)
                    {
                        return(false);
                    }
                    blnum += 4;
                    input.DropBits(4);
                    blLens = new byte[19];
                    ptr    = 0;
                    //          System.err.println("BLNUM: "+blnum);
                    mode = BLLENS;
                    goto case BLLENS;                                     // fall through

                case BLLENS:
                    while (ptr < blnum)
                    {
                        int len = input.PeekBits(3);
                        if (len < 0)
                        {
                            return(false);
                        }
                        input.DropBits(3);
                        //          System.err.println("blLens["+BL_ORDER[ptr]+"]: "+len);
                        blLens[BL_ORDER[ptr]] = (byte)len;
                        ptr++;
                    }
                    blTree = new InflaterHuffmanTree(blLens);
                    blLens = null;
                    ptr    = 0;
                    mode   = LENS;
                    goto case LENS;                                     // fall through

                case LENS:
                {
                    int symbol;
                    while (((symbol = blTree.GetSymbol(input)) & ~15) == 0)
                    {
                        /* Normal case: symbol in [0..15] */

                        //            System.err.println("litdistLens["+ptr+"]: "+symbol);
                        litdistLens[ptr++] = lastLen = (byte)symbol;

                        if (ptr == num)
                        {
                            /* Finished */
                            return(true);
                        }
                    }

                    /* need more input ? */
                    if (symbol < 0)
                    {
                        return(false);
                    }

                    /* otherwise repeat code */
                    if (symbol >= 17)
                    {
                        /* repeat zero */
                        //            System.err.println("repeating zero");
                        lastLen = 0;
                    }
                    else
                    {
                        if (ptr == 0)
                        {
                            throw new SharpZipBaseException();
                        }
                    }
                    repSymbol = symbol - 16;
                }
                    mode = REPS;
                    goto case REPS;                                     // fall through

                case REPS:
                {
                    int bits  = repBits[repSymbol];
                    int count = input.PeekBits(bits);
                    if (count < 0)
                    {
                        return(false);
                    }
                    input.DropBits(bits);
                    count += repMin[repSymbol];
                    //            System.err.println("litdistLens repeated: "+count);

                    if (ptr + count > num)
                    {
                        throw new SharpZipBaseException();
                    }
                    while (count-- > 0)
                    {
                        litdistLens[ptr++] = lastLen;
                    }

                    if (ptr == num)
                    {
                        /* Finished */
                        return(true);
                    }
                }
                    mode = LENS;
                    goto decode_loop;
                }
            }
        }